# Rotary carves not centered **URL:** \ **Category:** 🌀 Rotary Axis\ **Created:** [June 6, 2026, 3:53pm UTC](https://forum.sienci.com/t/rotary-carves-not-centered/26530 "2026-06-06T15:53:12Z")\ **Posts on this page:** 20\ **Page:** 1
**Author:** ![cncConfusion](https://forum.sienci.com/user_avatar/forum.sienci.com/cncconfusion/32/12731_2.png) [@cncConfusion](https://forum.sienci.com/u/cncConfusion)\ **Post date:** [June 6, 2026, 3:53pm UTC](https://forum.sienci.com/t/rotary-carves-not-centered/26530/1 "2026-06-06T15:53:12Z")
Hello all, I have recently added the vortex rotary to my Altmill 4x4. While it seems to work relatively well, I cannot seem to get it to turn a piece with a center through hole exactly centered. I have checked that the X and Z axis are exactly zeroed and aligned using a fine tipped carving bit. I have noticed that the chuck seems to have a bit of runout and the tail stock seems to tilt up and back when tightening it up to secure it. Has anyone else had this issue and could provide me some advice on how to remedy this issue? ![IMG_9375 (1)](https://forum.sienci.com/uploads/default/original/2X/4/45a68b3fdc281f2eec8c4fb4a7f2c1fb2583c8b7.jpeg) ![IMG_9374 (1)](https://forum.sienci.com/uploads/default/original/2X/f/f46ffcb902f584857772f5d3b2f5c15754d568bb.jpeg) ---
**Author:** ![cncConfusion](https://forum.sienci.com/user_avatar/forum.sienci.com/cncconfusion/32/12731_2.png) [@cncConfusion](https://forum.sienci.com/u/cncConfusion)\ **Post date:** [June 6, 2026, 4:13pm UTC](https://forum.sienci.com/t/rotary-carves-not-centered/26530/2 "2026-06-06T16:13:37Z")
Just for clarification, I predrilled the through hole so that I could then center that hole on the rotary. Hopefully that makes sense. Seems to me that even if the hole I drilled was not exactly in the center of the stock that as long as the carve is inside of the stock diameter (which it is - stock is 1.25" model is 1’) then the hole should be exactly centered after the carve. Am I wrong in my thinking here? ---
**Author:** ![gwilki](https://forum.sienci.com/user_avatar/forum.sienci.com/gwilki/32/366_2.png) [@gwilki](https://forum.sienci.com/u/gwilki)\ **Post date:** [June 6, 2026, 4:56pm UTC](https://forum.sienci.com/t/rotary-carves-not-centered/26530/3 "2026-06-06T16:56:34Z")
@cncConfusion Your thinking is correct - maybe. 😀 You pre-drill the hole. It does not need to be centered. However, how are you then holding the piece in the vortex? You cannot simply chuck it up. ---
**Author:** ![cncConfusion](https://forum.sienci.com/user_avatar/forum.sienci.com/cncconfusion/32/12731_2.png) [@cncConfusion](https://forum.sienci.com/u/cncConfusion)\ **Post date:** [June 6, 2026, 5:15pm UTC](https://forum.sienci.com/t/rotary-carves-not-centered/26530/4 "2026-06-06T17:15:10Z")
Using a bolt in the chuck end and the hole is the same as the tail stock pin so it fits in there perfectly. ---
**Author:** ![cncConfusion](https://forum.sienci.com/user_avatar/forum.sienci.com/cncconfusion/32/12731_2.png) [@cncConfusion](https://forum.sienci.com/u/cncConfusion)\ **Post date:** [June 6, 2026, 5:31pm UTC](https://forum.sienci.com/t/rotary-carves-not-centered/26530/5 "2026-06-06T17:31:00Z")
![Screenshot 2026-06-06 122854](https://forum.sienci.com/uploads/default/original/2X/6/647468b9e5e0f6156f1226dafe7989364bef846b.jpeg) I have this on the way to see if that makes any difference. ---
**Author:** ![gwilki](https://forum.sienci.com/user_avatar/forum.sienci.com/gwilki/32/366_2.png) [@gwilki](https://forum.sienci.com/u/gwilki)\ **Post date:** [June 6, 2026, 5:54pm UTC](https://forum.sienci.com/t/rotary-carves-not-centered/26530/6 "2026-06-06T17:54:21Z")
@cncConfusion As long as the bolt is running true, your setup should work. You’ve said that X and Z are set. Does this mean that your Vortex runs parallel to the Y rail? The chuck should not have any visible runout. Make sure that, when the jaws are fully closed, that the meet in the exact centre. The can be off quite easily. I’ve done many pieces on the Vortex and some pens, which require a fair degree of precision. I’ve never had an off-centre issue. ps. I forgot to ask how you are designing your piece and if it is a 3D model, how you are centering it in the material. ---
**Author:** ![cncConfusion](https://forum.sienci.com/user_avatar/forum.sienci.com/cncconfusion/32/12731_2.png) [@cncConfusion](https://forum.sienci.com/u/cncConfusion)\ **Post date:** [June 6, 2026, 8:42pm UTC](https://forum.sienci.com/t/rotary-carves-not-centered/26530/7 "2026-06-06T20:42:55Z")
Sorry, I meant Y and Z. ( **EDIT** Mounted parallel with the X axis) When I check the alignment with the fine point bit they are pretty much dead on. I’m pretty sure the chuck jaws are centered as well but I will double check that once again and attach pictures. The piece is setup in Vcarve Pro and yes it is centered in the stock but I will double check that as well and post a picture. I will also post the runout of the chuck when I get time to check it again. ---
**Author:** ![gwilki](https://forum.sienci.com/user_avatar/forum.sienci.com/gwilki/32/366_2.png) [@gwilki](https://forum.sienci.com/u/gwilki)\ **Post date:** [June 6, 2026, 9:36pm UTC](https://forum.sienci.com/t/rotary-carves-not-centered/26530/8 "2026-06-06T21:36:07Z")
@cncConfusion I think we may be talking at cross purposes. If your Vortex is mounted on the table parallel to the X rail, then you set Y0 and Z0 using gSender’s probe module. You set X0 manually by jogging in X to wherever you want to start your cut. Is this what you are doing, or is your Vortex mounted parallel to the Y rail? ---
**Author:** ![cncConfusion](https://forum.sienci.com/user_avatar/forum.sienci.com/cncconfusion/32/12731_2.png) [@cncConfusion](https://forum.sienci.com/u/cncConfusion)\ **Post date:** [June 7, 2026, 12:29am UTC](https://forum.sienci.com/t/rotary-carves-not-centered/26530/9 "2026-06-07T00:29:03Z")
@gwilki as you can tell, my handle rings true 🤣 ---
**Author:** ![gwilki](https://forum.sienci.com/user_avatar/forum.sienci.com/gwilki/32/366_2.png) [@gwilki](https://forum.sienci.com/u/gwilki)\ **Post date:** [June 7, 2026, 12:33am UTC](https://forum.sienci.com/t/rotary-carves-not-centered/26530/10 "2026-06-07T00:33:16Z")
@cncConfusion No worries. 😀 The usual set up is to have the Vortex at the front of the table, running parallel with the X rail. There is no rule, though. I’ll be interested to look at your pics to see if we can figure out what’s going wrong. It’s likely something simple. 🤞 ---
**Author:** ![cncConfusion](https://forum.sienci.com/user_avatar/forum.sienci.com/cncconfusion/32/12731_2.png) [@cncConfusion](https://forum.sienci.com/u/cncConfusion)\ **Post date:** [June 7, 2026, 12:35am UTC](https://forum.sienci.com/t/rotary-carves-not-centered/26530/11 "2026-06-07T00:35:53Z")
@gwilki Yes, mounted parallel to the X axis. Set the Y and Z with the gSender probe module. Manually set X to center of my work piece. I’m about to go out and get a bunch of pictures for ya. ---
**Author:** ![cncConfusion](https://forum.sienci.com/user_avatar/forum.sienci.com/cncconfusion/32/12731_2.png) [@cncConfusion](https://forum.sienci.com/u/cncConfusion)\ **Post date:** [June 7, 2026, 3:45am UTC](https://forum.sienci.com/t/rotary-carves-not-centered/26530/12 "2026-06-07T03:45:21Z")
@gwilki Ok so are some pics and videos of the run out. Hopefully these make sense of some sort. It kinda looks like the Z height is off just a bit, used a feeler gauge and there was about .045 between the tips. So maybe this is the culprit?? 🧐 I’ll have to figure out how to add a video on here to show the runout on the chuck. Let me know if you want any other pictures. ![Tips at tailstock](https://forum.sienci.com/uploads/default/original/2X/7/730ab3467cc21f2781aa630a862a077b4c845ef3.jpeg) ![Tips at chuck](https://forum.sienci.com/uploads/default/original/2X/2/2575f5944bf209ebe74e7305c84c8e4d9875b2ab.jpeg) ![Screenshot 2026-06-06 224919](https://forum.sienci.com/uploads/default/original/2X/d/d7c51a405fcbda71e9034da4f6978d4d8586bcbd.jpeg) ---
**Author:** ![gwilki](https://forum.sienci.com/user_avatar/forum.sienci.com/gwilki/32/366_2.png) [@gwilki](https://forum.sienci.com/u/gwilki)\ **Post date:** [June 7, 2026, 11:20am UTC](https://forum.sienci.com/t/rotary-carves-not-centered/26530/13 "2026-06-07T11:20:59Z")
@cncConfusion Before going any further, please keep in mind that I am not Sienci tech support. I’ll do all I can, but you may need to open a support ticket in the end. 1. It looks like Z0 is off equally at both the headstock and tailstock ends, correct? So, that would rule out that the Vortex is slanted. No real help. Just an observation. 2. I assume that you are setting Z0 using the probing function in gSender. Correct? 3. You are using the stock chuck from Sienci? 4. What bit are you using to set Z0? I would try setting Z0 manually and rounding a scrap piece of material around a drilled hole to confirm that the issue is Z0 being off using the probe. ---
**Author:** ![cncConfusion](https://forum.sienci.com/user_avatar/forum.sienci.com/cncconfusion/32/12731_2.png) [@cncConfusion](https://forum.sienci.com/u/cncConfusion)\ **Post date:** [June 7, 2026, 1:57pm UTC](https://forum.sienci.com/t/rotary-carves-not-centered/26530/14 "2026-06-07T13:57:25Z")
@gwilki I totally understand that you are just here to try and help my confused a$$.. That being said, your are a f’ing genius! No I was not using the stock chuck, I had switched it to a 3 jaw self centering one for ease of centering materials. I did not think about the specs being slightly different on the OD of the chuck. So yes, there is a difference .09 so half that is .045 which basically exactly how much it seems to be off!! For the purpose of the test that I attached pictures of, I used that same bit to set the Y and Z zero. Still seems weird though that if the program is auto detecting the zero that it would matter, yes I use the X and Y rotary zero functions in the rotary tab. Here are the pictures of the chucks, bigger one is the stock 4 jaw. ![3 jaw aftermarket](https://forum.sienci.com/uploads/default/original/2X/3/3675a1e27d0262b105dbc815804cefbbe9a18782.jpeg) ![4 jaw stock](https://forum.sienci.com/uploads/default/original/2X/e/e908f39f9dcade620bbad57bc65b6bfd7f57b572.jpeg) I will put the 4 jaw back on there and test the z again and run another handle off as a test with the new center drive that should be showing up today and see what happens. Thanks for all your time and patience helping me figure this out!! ---
**Author:** ![gwilki](https://forum.sienci.com/user_avatar/forum.sienci.com/gwilki/32/366_2.png) [@gwilki](https://forum.sienci.com/u/gwilki)\ **Post date:** [June 7, 2026, 2:03pm UTC](https://forum.sienci.com/t/rotary-carves-not-centered/26530/15 "2026-06-07T14:03:02Z")
@cncConfusion You’re welcome. I’m sure that is the issue. gSender computes where the Z centre point is based on the height of the stock chuck from that centre. It uses a hard coded distance. If you change the distance by using a chuck of a different diameter, gSender does not accommodate that difference. Unlike the touchplate module in gSender, I don’t believe that there is a setting that you can change to reflect a different chuck size. I can’t tell which chuck is smaller. If it is your new chuck, you could always shim it up with metal foil tape of something. If your new chuck is larger - never mind. 😀 ---
**Author:** ![DavidB](https://forum.sienci.com/letter_avatar_proxy/v4/letter/d/76d3ee/32.png) [@DavidB](https://forum.sienci.com/u/DavidB)\ **Post date:** [June 7, 2026, 2:05pm UTC](https://forum.sienci.com/t/rotary-carves-not-centered/26530/16 "2026-06-07T14:05:24Z")
That seems like an easy fix for gSender to at least provide user ability to change that value. It is common on lathes for people to have different chucks then what comes with your lathe. ---
**Author:** ![cncConfusion](https://forum.sienci.com/user_avatar/forum.sienci.com/cncconfusion/32/12731_2.png) [@cncConfusion](https://forum.sienci.com/u/cncConfusion)\ **Post date:** [June 7, 2026, 2:19pm UTC](https://forum.sienci.com/t/rotary-carves-not-centered/26530/18 "2026-06-07T14:19:01Z")
@DavidB there may be a way to adjust that but I am too new to this software to know for sure. Hopefully someone here knows more and if not I will reach out to Sienci about it. ---
**Author:** ![cncConfusion](https://forum.sienci.com/user_avatar/forum.sienci.com/cncconfusion/32/12731_2.png) [@cncConfusion](https://forum.sienci.com/u/cncConfusion)\ **Post date:** [June 7, 2026, 5:43pm UTC](https://forum.sienci.com/t/rotary-carves-not-centered/26530/19 "2026-06-07T17:43:02Z")
@gwilki The stock 4 jaw is bigger than the replacement 3 jaw I put on. I put the 4 jaw back on and reran the zero macros and this is the result. ![IMG_9395](https://forum.sienci.com/uploads/default/original/2X/a/a19c7e32a5f21df747ef8bfc859d4ed3141ce98c.jpeg) ![IMG_9396](https://forum.sienci.com/uploads/default/original/2X/a/a073432b0f7c25d2fef3502bd3030122186bd5aa.jpeg) Looks pretty much dead on. So now if I wanted to use the 3 jaw chuck I guess I could just zero it with the built in macro, then manually adjust it for the difference…🤔 🤔 🤔 🧐 ---
**Author:** ![gwilki](https://forum.sienci.com/user_avatar/forum.sienci.com/gwilki/32/366_2.png) [@gwilki](https://forum.sienci.com/u/gwilki)\ **Post date:** [June 7, 2026, 6:12pm UTC](https://forum.sienci.com/t/rotary-carves-not-centered/26530/20 "2026-06-07T18:12:57Z")
@cncConfusion Yes, it would be easy enough to do. Once you know the variance, you could write a simple macro and attach it to one of the buttons on the estop, if you like. It would be the same idea as using a macro to jog the machine to compensate for an offset between the router and the laser, for example. I use a crosshair laser to find XY0 as it’s easier than trying to set it with an end mill (old eyes). Then I simply run a macro that compensates for the offset between the crosshair laser location and the centre of the spindle. ps. Or, you could shim a spot on the 3-jaw chuck to mimic the diameter of the 4-jaw chuck. ---
**Author:** ![cncConfusion](https://forum.sienci.com/user_avatar/forum.sienci.com/cncconfusion/32/12731_2.png) [@cncConfusion](https://forum.sienci.com/u/cncConfusion)\ **Post date:** [June 7, 2026, 10:48pm UTC](https://forum.sienci.com/t/rotary-carves-not-centered/26530/21 "2026-06-07T22:48:03Z")
@gwilki Well while our theory about the different chuck size seemed very plausible, it seems to have not panned out. I ran 2 more samples running the exact same tool path gcodes: One with the Sienci 4 jaw chuck (jaws are perfectly centered) using a counter sink bit as a mounting device (like you see in the above pictures) One with the Sienci 4 jaw chuck and the new 4 prong center drive with the 8mm smooth shaft. Both came out pretty much the identical, and off centered still.🤦 🤦 🤦 I’m open to any more suggestions, otherwise I’ll put in a support ticket and see what they have to say. From what I can measure they are about .04 of still to one side. ![IMG_9397](https://forum.sienci.com/uploads/default/original/2X/7/75ef58ce735d9993b5aa48c160466280d308989e.jpeg) ![IMG_9398](https://forum.sienci.com/uploads/default/original/2X/f/f6f02a19ad35a18489e946a99f06206676e0c051.jpeg) [Next page](https://forum.sienci.com/t/rotary-carves-not-centered/26530.md?page=2)